<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Promise</title>
</head>
<body>
    <script>
        // Promis相当于一个构造函数
        // 实例化Promise对象的then方法
        const p = new Promise(function(resolve,reject){
            setTimeout(function(){
                let err = '数据读取失败';
                reject(err);
            },1000);
        });
        p.then(function(value){
console.log(value);
        },function(reason){
console.error(reason);
        })
    </script>
</body>
</html>